The invention concerns a device and a method for controlling the undercarriage of a vehicle with means for the adjustment of undercarriage parameters, such as, for example, the spring travel or the spring constant, in accordance with computed control signals. The invention is suitable for use in motor vehicles, particularly for use in passenger vehicles.
Undercarriage control systems have been used increasingly in passenger vehicles during recent years to enhance the comfort and safety of these vehicles. Such an undercarriage control system permits, for example, an adjustable damping characteristic or leveling control of the vehicle body independently of vehicle loading, in order to adapt the undercarriage to different road conditions.
Undercarriage control systems are classified according to their control characteristic as passive, adaptive, semiactive and active. An overview of the various control characteristics is provided in R. Kallenbach et al., Optimierung des Fahrzeugverhaltens mit semiaktiven Fahrwerkregelungen [Optimization of vehicle behavior by means of semiactive undercarriage control systems], VDI [Verein Deutscher Ingenieure; Association of German Engineers] Reports No. 699, 1988, pp. 121-135. The technical complexity of undercarriage control systems and their resultant cost depends on the desired control characteristic, and generally increase continuously from passive to active undercarriage control. The cited document describes in particular the optimization of vehicle behavior by means of semiactive undercarriage control systems, which offer a marked cost advantage over active undercarriage control systems.
A modern concept of undercarriage control is described in W. Schramm et al., "A high-performance concept for active undercarriage control with reduced energy demand," ATZ Automobiltechnische Zeitschrift 94 (1992), pp. 392-403. In particular, this article introduces a new concept for semiactive undercarriage control, consisting of a fully load-bearing hydropneumatic suspension with actuators in a shutoff-cylinder arrangement.
The sensing devices currently used in undercarriage control consist of travel sensors that determine the spring travel of the undercarriage at each axle, preferably at each wheel. From the present standpoint, optimum measurement acquisition would require measurement of the spring travel at each wheel suspension. Despite this high technical complexity and the associated high cost, due in particular to the use of a large number of sensors and a high available computation speed, as well as the provision of high-performance hydraulic, pneumatic and/or electrical final control elements to achieve a high control speed, the prior art undercarriage control systems are unable to achieve optimal and sufficiently rapid detection of all the situations that can arise during driving.
From digital image processing, methods and algorithms are known that can be used to identify at least partly preestablished structures and patterns in complex images and to filter them out of these images. Such methods can be used, for example, in medical technology for the automatic recognition of cancer cells in tissue specimens.
From automotive measurement technology, methods of distance measurement are known, for example involving the use of electromagnetic waves in various frequency ranges. In addition, modern navigational systems can be used in motor vehicles to furnish data regarding position and/or traffic flow.
The problem underlying the invention is to provide a device and a method for controlling the undercarriage of a motor vehicle that ensures a high degree of driving safety and driving comfort. In particular, the undercarriage control system should react quickly and optimally to all existing and immediately impending driving situations. Furthermore, the technical complexity and the associated production, installation and operating costs should be as low as possible.